Department of Aquaculture, National Pingtung University of Science and Technology, Pingtung, Taiwan.
J Appl Microbiol. 2009 Sep;107(3):1031-41. doi: 10.1111/j.1365-2672.2009.04284.x. Epub 2009 Mar 25.
To isolate and identify a benefic bacterium, Bacillus subtilis E20, from natto (fermented soybeans), and incorporate it into shrimp feed to promote shrimp growth performance.
A protease-producing bacterium, E20, isolated from natto was identified as B. subtilis by an API 50 CHB kit and the 16S rDNA sequence. B. subtilis E20 was able to grow at a broad range of temperatures (10-50 degrees C), pH values (5-10), and NaCl levels (0-9%). The best culture conditions for B. subtilis E20 to produce the protease were 40 degrees C, a pH of 6-8 and 0% NaCl. No shrimp died after being injected with B. subtilis E20 [up to 10(9) colony-forming units (CFU) per shrimp]. Bacillus subtilis E20 was incorporated in diets at the levels of 0 (control), 10(6), 10(7), and 10(8) CFU kg(-1) for shrimp grow-out culture, and results showed that after feeding on B. subtilis E20-containing diets (10(8) CFU kg(-1) of diet), shrimp had excellent growth performance and production compared to the control because protease activities in the digestive tract were improved by B. subtilis E20.
Bacillus subtilis E20 isolated from natto is a great protease producer and is able to improve shrimp growth performance through increasing the digestibility of food.
Results suggest that B. subtilis E20 is a potential candidate for use as a probiotic to improve shrimp growth performance, and consequently reduce feed costs.
从纳豆（发酵大豆）中分离并鉴定出一种有益细菌枯草芽孢杆菌 E20，并将其纳入虾饲料中以促进虾的生长性能。
从纳豆中分离出一种产蛋白酶的细菌 E20，通过 API 50 CHB 试剂盒和 16S rDNA 序列鉴定为枯草芽孢杆菌。枯草芽孢杆菌 E20 能够在较宽的温度（10-50°C）、pH 值（5-10）和 NaCl 水平（0-9%）下生长。枯草芽孢杆菌 E20 产生蛋白酶的最佳培养条件为 40°C、pH 值 6-8 和 0%NaCl。将枯草芽孢杆菌 E20 注射到虾体内后，虾没有死亡[每只虾高达 10（9）个菌落形成单位（CFU）]。将枯草芽孢杆菌 E20 掺入饲料中，用于虾养殖生长阶段，浓度分别为 0（对照）、10（6）、10（7）和 10（8）CFU kg（-1），结果表明，与对照组相比，摄食含有枯草芽孢杆菌 E20 的饲料（饲料中含有 10（8）CFU kg（-1）枯草芽孢杆菌 E20）的虾具有出色的生长性能和产量，因为枯草芽孢杆菌 E20 提高了消化道中蛋白酶的活性。
从纳豆中分离出的枯草芽孢杆菌 E20 是一种优秀的蛋白酶产生菌，能够通过提高食物的消化率来改善虾的生长性能。
结果表明，枯草芽孢杆菌 E20 是一种有潜力的益生菌候选物，可用于提高虾的生长性能，从而降低饲料成本。
